1. Field of the Invention
The present invention relates to an ultrasonic diagnosis device with an endoscope having an ultrasonic diagnosis function.
2. Description of the Related Art
Such an ultrasonic diagnosis device is known as being a combination of an endoscope with an ultrasonic scanning mechanism. Generally, an ultrasonic diagnosis device includes an insertion portion which is to be inserted into a coelom in the body of a human being, or the like cavity, and of which the front end region accommodates an ultrasonic probe so as to be rotatable about the center axis thereof. For causing the rotation of the probe, a drive means is formed of a motor and arranged in the drive portion outside of the cavity, while a power transmission means for drivably connecting the motor with the probe is formed of a hollow flexible shaft passed through the insertion portion. On the other hand, signal wires from the probe are passed through the interior space of the flexible shaft, and extend to an external ultrasonic observation device. Needless to say, ultrasonic scanning within the cavity is carried out by rotating the probe by means of the motor. Further provided is an optical observation system in which the optical image obtained by objective lens is guided to eyepiece lens by image guide fibers.
Conventionally, as the ultrasonic probe is arranged in the front end region of the insertion portion of the endoscope, and the flexible drive shaft occupies the center space of the insertion portion, the optical observation means has to be arranged on the side wall of the front end region. Hence, the direction of the visual field of the optical observation system is limited and has to extend transversely. The dead angle includes the direction in which the endoscope is to be inserted, so that it is difficult to manipulate the endoscope in the cavity. Particularly, when the known endoscope is to be used in the large intestine, or in the like organs with a complex undulation of the cavity, due to the difficulties in the manipulation arising from the limitation of the visual field, the insertion of the endoscope beyond the rectum is almost impossible, or accompanies a substantial risk even when possible.
An arrangement is known wherein the objective lens is arranged in the front end surface of the insertion portion of the endoscope, such that the direction in which the endoscope is to be inserted coincides with the optical visual field. Such an arrangement, however, suffers from the problem that the ultrasonic field is interrupted by the shadow of the optical observation means. It is thus impossible to obtain an ultrasonic field covering the entire angular range within a plane which is intersected perpendicularly by the axis of the front end of the endoscope, and practically obtainable field covers only the angular range of the order of 180.degree.. As a result, in order to obtain a complete ultrasonic diagnosis image of the desired location within the coelom, it was necessary to carry out a complex and burdensome manipulation of the endoscope in the coelom, such as twisting or rotational movement.